The volume drop on this project had been a real disappointment, since the stock circuit sounds very good, but way too low in level to be usable. This weekend I simulated the circuit in LTSpice and found a couple mods worth experimenting with to achieve unity or even a boost in volume level:
If you add a much smaller value resistor (470 ohm-2.2k) in parallel to R7/10k the overall output level increases. I used a 1.5k (in parallel to the 10k = 1.3k), which doesn't hit the second op amp with too hot of a signal. Additionally, if you change the Mix pot to a higher value it will also increase the output level for all delay mix levels without changing the width of adjustment too much. I used a B25k, which in combination with the R7 change made the pedal completely gig-able with a few dBs of signal boost overall. With these two changes, the build doc's R48 18k to 47k swap isn't necessary. I thought the R48 swap changed the character of the stock pedal too much anyway by adding a lot more low frequencies with only getting a modest gain in output level.
The one trade-off I've found with the above mods is that the sweep of the Mix control changes, so the lower delay mix levels are a little harder to dial in, but I normally use delay levels set pretty high, same or louder than the clean signal, so it's not an issue for me. With the component values I chose, I don't hear any increase in distortion by hitting that last opamp stage with more signal, but I use a Tele with passive vintage output pickups, so YMMV.
If you add a much smaller value resistor (470 ohm-2.2k) in parallel to R7/10k the overall output level increases. I used a 1.5k (in parallel to the 10k = 1.3k), which doesn't hit the second op amp with too hot of a signal. Additionally, if you change the Mix pot to a higher value it will also increase the output level for all delay mix levels without changing the width of adjustment too much. I used a B25k, which in combination with the R7 change made the pedal completely gig-able with a few dBs of signal boost overall. With these two changes, the build doc's R48 18k to 47k swap isn't necessary. I thought the R48 swap changed the character of the stock pedal too much anyway by adding a lot more low frequencies with only getting a modest gain in output level.
The one trade-off I've found with the above mods is that the sweep of the Mix control changes, so the lower delay mix levels are a little harder to dial in, but I normally use delay levels set pretty high, same or louder than the clean signal, so it's not an issue for me. With the component values I chose, I don't hear any increase in distortion by hitting that last opamp stage with more signal, but I use a Tele with passive vintage output pickups, so YMMV.
I'm not sure I can test these outside of a project. Any ideas for a decent DIY project that I can use at least one of the BBDs, and maybe all four if they're all good? Can a SAD512D simply replace other BBDs like MN3017, MN3019, MN3007, MN3009 in projects?
